testing/melange: upgrade to 0.20.1

https://github.com/chainguard-dev/melange/releases/tag/v0.20.1

testing/melange/APKBUILD

@@ -14,14 +14,9 @@ subpackages="
 	"
 source="https://github.com/chainguard-dev/melange/archive/v$pkgver/melange-$pkgver.tar.gz"
 
-prepare() {
-	default_prepare
-	go mod tidy
-}
-
 build() {
 	mkdir build
-	go build -o build/ ...
+	go build -o build/ .
 
 	for i in bash fish zsh; do
 		./build/melange completion $i > melange.$i